The present invention relates in general to a sole assembly for a sports shoe, and more particularly to a sole assembly formed of three layers of an upper layer, a middle layer and a lower layer, especially for an indoor shoe.
A sports shoe is generally divided into two categories; an outdoor shoe and an indoor shoe. In the soles of these shoes, various structures and different materials have been used according to the characteristics of sports.
In an outdoor shoe, an outsole made of synthetic rubber has been used from the viewpoint of gripping abilities, and an outsole made of synthetic resin has been used from the viewpoint of durability. Further, in an outsole made of synthetic resin and having increased gripping properties, cleats or spikes made of metal or synthetic resin have been provided under the bottom surface of the outsole.
On the other hand, in an indoor shoe, gripping abilities, shock absorbing properties, and lighter weight become more important because indoor sports typically require hard movements in a vertical and horizontal direction. Thus, an outsole made of synthetic rubber has been employed and a sole has been constructed from two or three layers.
Also, an outsole has been formed of a plurality of materials and various improvements have been introduced into an outsole in order to further improve properties of the ground surface or sole surface of the outsole.
Japanese utility model examined publication No. 62-27123 shows a sole having a sole body made of hard synthetic resin, a plurality of chips made of hard synthetic resin and a plurality of rubber chips, which are integrally formed with each other through fabric.
Japanese utility model examined publication No. 1-27684 discloses a sole made of synthetic resin, studs formed integrally with the sole and made of synthetic resin, and rubber studs fitted into through holes formed in the sole.
Japanese utility model unexamined publication No. 7-30709 shows a sole having two layers formed of an inner sole and an outsole of hard synthetic resin, tip ends of a plurality of protrusions formed integrally with the lower surface of the inner sole extend into respective through holes formed in the outsole, and compressible, elastic members are interposed between the inner sole and the outer sole.
Japanese patent application examined publication No. 8-22241 shows a sole with an outsole having a plurality of cleats provided thereon and having thin-walled portions formed around the cleats on the outsole.
The sole shown in publication No. 62-27123 is directed to achieving non-slipping properties through rubber chips and wear resistance through chips made of hard synthetic resin. Two kinds of chips are required to control non-slipping properties and wear resistance of the sole, and fabrics are needed to make the chips integrated with the sole.
In the sole disclosed in publication No. 1-27684, both plastic studs and rubber studs protrude from the bottom surface or sole surface of the sole, and such a sole is suitable only for outdoor sports such as baseball, soccer or the like, as is described in the publication.
The sole shown in publication No. 7-30709 is directed to absorbing shock load during activities through elastic deformation of an elastic member provided between the inner sole and the outsole and to achieving gripping power relative to the ground through the protrusions of the inner sole that come into contact with the ground. As is described in the publication, this sole is applicable only to an outdoor shoe such as a tennis shoe.
The sole shown in publication No. 8-22241 is directed to improving non-slipping properties by making a thickness of the outsole thinner at the peripheries of the cleats so that the cleats can incline independently. This sole is also applicable only to an outdoor shoe.
The present invention is directed to providing a sole assembly for a sports shoe, especially for an indoor shoe, which can improve gripping abilities and shock absorbing properties.
The sole assembly according to the present invention is constructed from an upper layer, a middle layer and a lower layer that are integrated with each other. The upper and lower layers are formed of a soft elastic material, and the middle layer has a sheet formed of synthetic rubber or resin of a hardness greater than those of the upper and lower layers. The sheet has a plurality of protrusions or cleats depending therefrom, and the lower layer has a plurality of through holes receiving respective cleats.
According to the present invention, the lower layer formed of a soft elastic material improves gripping abilities at the time of kicking or pushing the ground and shock absorbing properties at the time of striking onto the ground. Also, the upper layer formed of a soft elastic material improves cushioning properties on landing and contact feeling of a foot. Moreover, since a sheet of a greater hardness is provided between the upper and lower layers, excessive depression of the upper and lower layers can be prevented at the time of loading a shock load, thereby impeding lateral deformation of the upper and lower layers to improve stability of a shoe.
Furthermore, in this case, the protrusions of the sheet inserted into the through holes of the lower layer come into contact with the ground, thus making gripping abilities and shock absorbing properties controllable.
In this case, since the protrusions are not provided in such a way to protrude overly from the sole surface, the sole assembly especially suitable for an indoor shoe can be achieved.
The protrusions may be formed of the same material as the sheet and formed integrally with the sheet. Alternatively, the protrusions may be formed of a different material than the sheet and combined with the sheet to form a unit.
A clearance may be formed between an outer circumferential surface of each protrusion and an inner circumferential surface of a respective associated through hole. In this case, the protrusions come to incline or deform laterally inside the respective through holes at the time of contacting the ground, thereby enabling an edge portion of a distal end of the protrusion to come into contact with the ground, which can further improve gripping abilities of the protrusion.
The protrusion is preferably in the shape of a truncated cone, whose diameter becomes gradually smaller as it goes toward a distal end of the protrusion. In this case, since a clearance between the protrusion and the through hole becomes greater as it goes toward a distal end of the protrusion, a distal end portion of the protrusion can incline or bend laterally in every direction on a contact plane after landing, thereby securing gripping abilities and shock absorbing properties in the whole direction on the contact plane.
The distal end of the protrusion may be flush with or below the contact surface of the lower layer. Alternatively, the distal end of the protrusion may protrude from the contact surface of the lower layer. The length of the protrusion relative to the thickness of the lower layer depends on the required gripping abilities, compressive hardness (or hardness to deform relative to the compressive force) of the lower layer, characteristics of sports, or weight of a shoe wearer.
In a preferred embodiment, a sheet is formed of a wavy corrugated sheet that has a wavy corrugation at least at a heel portion of the sheet. In this case, at the time of loading a shock load, a wavy corrugated portion of the corrugated sheet displays compression suppressing effect and prevents the upper and lower layers from being depressed excessively and deforming laterally, thereby further improving stability of a shoe. Moreover, in this case, prevention of depression of the upper and lower layers enables a transfer from landing to pushing the ground to occur smoothly. Thereby, each protrusion comes to transmit gripping power to the ground securely at the time of pushing or kicking the ground.